A young man does not fall in love with his sister though she be the most attractive girl he knows. Nor does her father fall in love with her, nor the mother with the son, or the son with the mother. Not only is there no sexual love between them, but the very idea of marriage fills their mind with unutterable horror, and in the occasional cases where such a marriage is made through ignorance of the relationship, both parties usually commit suicide, though they are guiltless of deliberate crime. Here we have the most striking and absolute proof that circumstances, habits, ideas, laws, customs, can and do utterly annihilate sexual love in millions of individuals. Why then should it be so unlikely that the laws and customs of the ancient Greeks, for instance, with their ideas about women and marriage, should have prevented the growth of sentimental love? Note the modesty of my claim. While it is certain that both the sensual and the sentimental sides of sexual love are stifled by the horror of incest, all that I claim in regard to ancient and primitive races is that the sentimental side of love was smothered by unfavorable circumstances and hindered in growth by various obstacles which will be described later on in this volume. Surely this is not such a reckless theory as it seemed to some of my critics. Like the other sentiments discussed in this chapter, the horror of incest has been found to be absent among races in various stages of development. Incestuous unions occurred among Chippewas and other American Indians. Of the Peruvian Indians, Garcilasso de la Vega says that some cohabited with their sisters, daughters, or mothers; similar facts are recorded of some Brazilians, Polynesians, Africans, and wild tribes of India. "Among the Annamese, according to a missionary who has lived among them for forty years, no girl who is twelve years old and has a brother is a virgin" (Westermarck, 292). Gypsies allow a brother to marry a sister, while among the Veddahs of Ceylon the marriage of a man with his younger sister is considered _the_ proper marriage. In the Indian Archipelago and elsewhere there are tribes who permit marriage between parents and their children. The legends of India and Hindoo theology abound in allusions to incestuous unions, and a nation's mythology reflects its own customs. According to Strabo the ancient Irish married their mothers and sisters. Among the love-stories of the ancient Greeks, as we shall see later on, there are a surprising number the subject of which is incest, indicating that that crime was of not infrequent occurrence. But it is especially by royal personages that incest has been practised. In ancient Persia, Parthia, Egypt, and other countries the kings married their own sisters, as did the Incas of Peru, for political reasons, other women being regarded as too low in rank to become queens; and the same phenomenon occurs in Hawaii, Siam, Burma, Ceylon, Madagascar, etc. In